单击日期选择器上的日期将显示valueMissing的自定义错误

document.getElementById('datePicker').addEventListener('change', function(event) {
    let selectedDate = event.target.value;
    if (!selectedDate) {
        event.target.setCustomValidity('valueMissing');
    } else {
        // 假设输入字段要求的格式是 YYYY-MM-DD
        let formattedDate = selectedDate.split('-').join('');
        event.target.value = formattedDate;
        event.target.setCustomValidity('');
    }
});

<input type="text" id="dateInput" required>
<input type="date" id="datePicker" onchange="updateDateInput()">

function updateDateInput() {
    let datePicker = document.getElementById('datePicker');
    let dateInput = document.getElementById('dateInput');
    dateInput.value = datePicker.value;
}

document.getElementById('datePicker').addEventListener('change', function(event) {
    let selectedDate = event.target.value;
    if (!selectedDate) {
        event.target.setCustomValidity('valueMissing');
    } else {
        // 自定义验证逻辑
        if (selectedDate < '2023-01-01') {
            event.target.setCustomValidity('Date must be after 2023-01-01');
        } else {
            event.target.setCustomValidity('');
        }
    }
});